Obama initially thought mandate had been struck down

In an address to the nation, President Obama said he didn't fight for the Affordable Care Act because it's good politics, and called on the country to avoid the political battle of two years ago and move forward. Presumptive Republican presidential nominee Mitt Romney responded to the court's decision, saying that the court may have ruled the law constitutional, but did not say that 'Obamacare' was good law or good policy. The Romney campaign has already raised more than $2 million since the health care decision was announced. NBC's Chuck Todd reports.

By NBC's Chuck Todd, Shawna Thomas, and Domenico Montanaro

It must have been a long 40 seconds.

Minutes after 10 o’clock this morning, as news of the health-care ruling was coming out, President Obama -- who does not get any forewarning from the Supreme Court on its decisions -- was, like much of the rest of the country, relegated to watching television.

He stood in front of a television, with a split screen of four different channels, when banners flashed on two cable networks showing that the law’s central tenet -- the mandate requiring all Americans to buy health insurance -- had been struck down, according to White House aides who briefed reporters today.

For about 40 seconds, the president believed that his landmark, legacy-defining legislative accomplishment, had been gutted.

That was until White House counsel Kathryn Ruemmler came into the room and gave the president two thumbs up -- the law had actually been upheld. She quickly explained to a confused president what had happened.

While others, including NBC News and MSNBC, reported the correct information, the White House also did have a government lawyer at the high court relaying information to Ruemmler.

Obama’s first call, according to White House aides, was to his Solicitor General Donald Verrilli to congratulate him. Verrilli, who argued the case before a sometimes contentious row of justices, had been mocked by some in the legal community for his handling of the case.

The president made it clear he was not among the doubters. He told Verrilli he always thought he had done an excellent job. Ruemmler got a hug.

On the details of the law, one aide stressed that some estimates show less than one percent of people will end up having to pay -- what’s now been labeled by the court as -- the health-care tax.

Aides believe the Medicaid portion of the decision is not particularly significant, because, in the past, when faced with such decisions (the Children’s Health Insurance Program, or CHIP, for example), the states usually end up enacting the laws.

The White House is also downplaying any kind of poll bump the president could get from the ruling. Advisers to the president believe the country is burned out on the health-care argument, the last thing people want is a bloody fight, and there's no way the GOP can repeal it without such a fight.

The White House also happily points out that Obama's challenger, presumptive Republican nominee Mitt Romney, put a mandate in place as governor of Massachusetts, and that now he's running away from it -- at least as federal law.

One aide also admitted that advisers had always assumed the Commerce Clause argument was the better way to get five justices on their side.

Of course, there's also the legislative reality that calling the mandate a "tax" would have made the law even less palatable when trying to pass it through Congress.